[CLIENT?] Saw enemy team chat

Just had a game where I was able to see a message from someone on the enemy team. Not only is there no [ALL] next to the message indicating that the message was intended for both teams, but I also have all chat off and double checked so during the time I took this screenshot. No other messages from the enemy team popped up in my chat feed that game, nor did any of my teammates comment on it so I'm guessing none of them saw it.

Neither I nor the speaker was dead at the time, so I can't so much as guess what played a factor in this as far as reproducing goes.